Nidec 800-84132 Series User manual

Page 1
Copyright © 2015 Kato Engineering, Inc. All rights reserved
Instruction Manual
Installation
Operation
Maintenance
Voltage Regulator
Magnetic Amplier (Three Phase)
P/N 800-84132-XX
12
14-19
23-25
28-31
Publication
351-01053-00 (April 1995)
Kato Engineering, Inc. |P.O. Box 8447 |Mankato, MN USA 56002-8447 | Tel: [phone]
[email protected] |www.KatoEngineering.com |Fax: [phone]

1
SECTION 1
INTRODUCTION AND
THEORY OF OPERATION
INTRODUCTION
The magnetic amplifier voltage regulator is designed
to operate with brushless synchronous 400 Hz
generators. The voltage regulator controls generator
voltage by regulating the amount of current it supplies
the exciter field.
SPECIFICATIONS
Input Power: single phase, 400 Hz, 120 Vac
Sensing: three phase, 400 Hz, 120-139, or 208-240
Vac
Output: continuous maximum: 55 Vdc, 4 amperes
Test Circuit: 50 Vdc (optional)
THEORY OF OPERATION
Note: Refer to drawings
A. Sensing
A sample of the generator output voltage is applied to
regulator sensing terminals E1, E2 and E3. Tap
setting H2 for 120 or 208 Vac and H3 for 139 or 240
Vac. This voltage is applied to sensing transformer T1
and T2, which proportionally reduces the voltage.
Regulators equipped for parallel operation also
include transformer T4. This circuit does not affect
voltage regulator operation in single unit operation if
the CT leads are shorted. (See B below.)
The reduced AC voltage is then fed to a rectifier
consisting of diodes D1 through D6. The rectifier
output, which is proportional to the sensing voltage, is
filtered by capacitor C1. It is then impressed across a
voltage divider circuit consisting of resistors R2 and
R4, voltage range set adjust potentiometer R3, and
the externally mounted voltage adjust rheostat. A
portion of this voltage is applied to the base of
transistor Q1 in the error detector circuit.
B. Sensing Circuit During Parallel Generator
Operation in Parallel Cross-Current Compensa-
tion Mode
Parallel cross-current compensation allows two or
more parallel generators to share reactive loads and
maintain constant system output voltage. The reac-
tive error signal developed in the external paralleling
circuit is added vectorially to the sensing voltage by
transformer T4. The circuit is phased such that a
generator with excessive excitation will decrease
excitation and an under-excited generator will in-
crease excitation. At balance, each generator will
carry its share of reactive load.
C. Error Detector
The error detector is a differential amplifier. Resistors
R11 and R14 in the emitter circuit of transistors Q1
and Q2 are of equal value. Therefore, when the base
voltage of Q1 is equal to the base voltage at transistor
Q2, Q1 and Q2 conduction will be equal. Transistor
Q2 is the reference voltage side of the error detector.
Its base voltage is kept constant by zener diode Z1.
The base voltage of Q1 is proportional to the sensing
voltage and the setting of the voltage adjust rheostat.
Q1 base voltage will therefore increase and decrease
in direct proportion to any increase or decrease in the
sensing voltage or change in the setting of the voltage
adjust rheostat. Operation of the error detector (Q1,
Q2), second stage differential amplifier (Q3, Q4), and
amplifier Q5, Q6 is as follows.
An increase of Q1 base voltage will decrease Q1s
collector voltage and increase Q2s collector voltage.
The differential collector voltage is directly connected
to the bases of Q3 and Q4. This voltage increases
Q3s collector current and decreases Q2s collector
current. The increase in Q3s collector current is also
an increase in base drive to the control current
amplifier transistors Q5 and Q6. The collector current
of Q5 and Q6 and the magnetic amplifier control
current increases, resulting in decreased magnetic
amplifier output. Conversely, a decrease in sensing
voltage results in lower conduction of transistors Q1,
Q3, Q5, and Q6, a decrease in control current and an
increase in magnetic amplifier output.
D. Power Stage
The output power stage of the voltage regulator
rectifies 400 Hz power and feeds a regulated amount
of dc power to the exciter field. The power output
stage consists of an electromagnetic filter (RFI), two
full-wave rectifiers (BR1 AND BR2) and two toroid
magnetic amplifiers (MA-1 and MA-2). The magnetic
amplifiers contain two windings wound about a
ferromagnetic core. The windings are: a power or
gate winding and a control winding C1 and C2. Field
excitation is controlled by operation of the magnetic
amplifiers as described in the paragraphs that follow
The single phase, 400 Hz, 120 Vac power applied to
regulator terminals L1 and L2 magnetizes the mag-
netic amplifier core. During the time the core is being

2
magnetized, it creates a back e.m.f. across the gate
winding, limiting current flow. As magnetism of the
core increases, the rate of change in flux decreases,
resulting in a decrease in back e.m.f. This action
continues until the core becomes fully magnetized
(saturation). At this point no further change in flux
density occurs. Resistance across the gate winding is
then limited by the series resistance of the gate
winding and field winding, and current flow is maxi-
mum. Control and regulation are accomplished by
resetting the core of the magnetic amplifier at some
point below saturation during the half-cycle the gate
winding is not conducting. This is done by applying dc
control current to magnetic amplifier control winding
(C1-C2) and is referred to as magnetic reset or bias.
Increasing the control current resets the magnetic
amplifier core further below saturation. The further
the core is reset below saturation the more back
e.m.f. will be present across the gate winding. Thus,
the less current will flow through the gate winding and
exciter field. The magnetic amplifier reacts in an
opposite manner when control current is decreased.
E. Stability
The voltage regulator includes a negative feedback
system stability circuit designed to prevent oscillation
(hunting) of the generator output voltage. The circuit
consists of capacitors C2, C5, resistors R5, R6, R16
and a stability adjust potentiometer R7 .
F. EMI Suppression
Filter RFI is included in the voltage regulator input
power circuit to reduce conducted EMI to negligible
levels.
G. Test Voltage (optional)
A dc voltage proportional to the set sensing voltage is
available at terminals A and F- as an option.

3
SECTION 2
INSTALLATION
SAFETY SUMMARY
WARNING
To prevent injury to personnel or damage to
equipment, this unit shall be installed only in
accordance with installation instructions and
wiring diagrams contained in the instruction
manual provided with this unit.
WARNING
When this unit is operating, 120 VAC and 120-139
or 208-240 VAC is present at the voltage regulator
assembly terminal board and internal circuitry. To
avoid accidental contact with lethal voltage, de-
energize the generator set starting circuit while
making electrical connections or repairs to this
equipment.
CAUTION
Meggers and high potential test equipment
should not be used. Incorrect use of such equip-
ment could destroy the rectifiers, transistors and
capacitors in the regulator.
LOCATION
The voltage regulator may be mounted in the generator
terminal box or remotely mounted. The enclosure in
which the regulator is to be mounted should be of
sufficient size to permit flow of air about all sides of the
regulator.
MOUNTING
Mounting holes are incorporated in the regulator base.
The regulator can be mounted in any position without
affecting its operating characteristics.
ELECTRICAL CONNECTIONS
The regulator must be connected to the generator
system as instructed in the paragraphs that follow and
as shown on the diagrams for the generator and control
system. Number 14 gauge or larger wire should be
used for all connections to the voltage regulator.
A. Regulator Input Power Terminals L1 and L2.
The nominal voltage applied to the regulator input
power stage (terminals L1 and L2) must be single
phase, 400 hertz, 120 volt ac. The input power may be
taken from any generator lines that provide the correct
voltage (line-to-line or line-to-neutral).
NOTE: When the generator output is different from
the preceding value, a power transformer must be
used to match the generator voltage to the required
regulator input. If excessive voltage is applied to the
regulator input terminals L1 and L2), destruction of
the rectifiers in the regulator could occur.
B. Fuse F1. The voltage regulator contains a 250
volt, 5 amp., ABC-5 type fuse located within a fuse
holder that is mounted on the voltage regulator
chassis. Replacement fuse must be a normal break
fuse of the same capacity. A time delay type fuse
should not be used.
C. Grounding. The dc output circuit to the exciter
field must not be grounded. Regulator chassis
grounding can be accomplished by solidly mounting
the voltage regulator onto a metal cubicle which in
turn is grounded, or by connecting a ground wire from
the regulator case to ground.
D. Regulator Sensing (Terminals E1, E2 and E3).
The voltage regulator is designed for three phase,
400Hz, 120-139 or 208-240 Vac sensing. Follow the
interconnection diagram provided with the generator
set.
E. Sensing Transformer (T1 and T2) . Verify that the
sensing transformers located in the voltage regulator
are connected as follows: Tap H2 for 120 or 208 Vac
and Tap H3 for 139 or 240 Vac.
F. Voltage Regulator dc output Terminals F+ and
F-. This circuit provides DC excitation to the exciter
field. Observe correct polarity. F- connects to exciter
field lead F1 (-) and F+ to exciter field lead F2 (+). In
applications where field wires are longer than a foot
or two, shielding by running the field lead through
one-half inch conduit is recommended.
G. Externally Mounted Voltage Adjust Rheostat
(Terminals R1 and R2). Connect the voltage adjust
rheostat as shown on the wiring diagram provided
with the generator set. Make certain rheostat contains
a jumper wire between its slider terminal 2 and the
rheostat end terminal 1. When correctly connected,
turning the rheostat clockwise increases generator
voltage output.
H. Paralleling Terminals (Terminals CT1 and CT2).
On voltage regulators with paralleling, connect these
terminals to the paralleling circuit as shown on the
system drawing. If used for single unit operation,
short terminal CT1 to CT2.

4
SECTION 3
CONTROLS ADJUSTMENT
PROCEDURES AND
VOLTAGE REGULATOR
OPERATING
PROCEDURES
SAFETY PRECAUTIONS
The precautions described in Section 2 must be
followed when inspecting, making internal adjust-
ments, or making repairs to this equipment.
VOLTAGE REGULATING SYSTEM CONTROLS
The voltage regulating system includes the external
voltage adjust rheostat for adjustment of generator
output voltage, a voltage range potentiometer R3
located on the circuit board that extends either the
minimum voltage limit or maximum voltage of the
voltage adjust circuit, and a stability control potenti-
ometer R7 located on the circuit board that provides
means of increasing or decreasing a stabilizing signal
to attain optimum response and system stability.
Adjustment procedures are as described in the
paragraphs that follow.
A. Voltage Adjustment. This adjustment is made
while the generator is running at rated frequency and
while no-load is applied. Turning the externally
mounted voltage adjust rheostat clockwise increases
generator output voltage. When it is turned in a
counterclockwise direction, a decrease in generator
output voltage should occur. Voltage is measured
during the adjustment procedure by observing the
generator voltmeter.
B. Voltage Range Adjustment. This adjustment
extends either the minimum voltage limit or the
maximum voltage limit of the external voltage adjust
rheostat. It is normally factory set at about 1/2 its
maximum travel. To limit maximum voltage adjust as
follows:
NOTE: In applications that include overvoltage
protection circuitry the maximum voltage setting
should be lower than the overvoltage trip setting.
1. Operate generator at rated frequency with no-load
applied. Turn the external voltage adjust to its maxi-
mum clockwise position.
NOTE: Turning R3 clockwise raises the maximum
voltage while turning it counterclockwise decreases
the maximum voltage.
2. Measure generator voltage using the generator
outputvoltage. If voltage is not the required maximum,
turnpotentiometer R3 in the appropriate direction until
3' voltmeter indicates output voltage is the required
maximum. This is the final adjustment of R3.
3. Turn external voltage adjust counterclockwise to
position where output voltage decreases to rated
value.
C. Stability Adjustment R7. This control is located
on the regulator printed circuit board. Adjust R7 only if
during operation oscillating voltage or slow response
occurs.
1. Slow Response. Turn R7 clockwise to position
where response is satisfactory. Test with load applied
and also with no-load applied. If oscillating voltage
occurs turn R7 clockwise past the point where
oscillation stops.
2. Voltage Oscillating. Turn R7 clockwise past the
position where oscillations stop. Test no-load and with
load applied.
NOTE: Slow response, loss of sensitivity and poor
regulation could occur if R7 is turned too far counter-
clockwise.
OPERATING PROCEDURES
The instructions that follow describe the procedures
to be followed during initial operation and during
subsequent operation of the unit. The preceding
chapters as well as the following procedures should
be reviewed and understood before system operation
is attempted. The system operator should also locate
all controls and adjustments pertinent to system
operation before attempting to operate the equip-
ment.
A. Initial operation
1. Open output circuit breaker or contactor. Initial
start-up should be made with no-load.
2. In applications where system includes overvoltage
devices or a field circuit breaker, make certain the
field circuit breaker and overvoltage circuit is not
tripped open.
3. In applications where system includes both auto-
matic voltage control, and manual voltage control set

5
mode selector switch to AUTO position for automatic
regulation.
4. Start the generator set and bring up to rated speed.
5. Verify generator voltage. Any of the following
conditions may occur:
a) Overvoltage  If this condition occurs adjust the
auto voltage adjust rheostat as described in para-
graph A, Voltage Adjustment. If condition persists,
stop the prime mover and determine cause of mal-
functions.
b) Undervoltage  If condition occurs adjust the
auto voltage adjust rheostat as described in para-
graph A, Voltage Adjustment. If condition persists,
stop the prime mover and determine cause of mal-
function.
c) No voltage buildup  If this condition exists and
an auto/manual switch is incorporated, stop the prime
mover, set auto/manual switch to manual position,
start generator set and see if voltage builds up.
NOTE: Alternative methods of testing to isolate faulty
operation and a troubleshooting chart are given in
Chapter 4.
d) Oscillating Voltage (Hunting)  If this condition
exists adjust stability control as described in para-
graph C, Stability Adjustment R7. If problem persists,
refer to troubleshooting procedures. Voltage hunting
can be caused by an unstable prime mover .
e) Voltage Unstable or Slow Response  Adjust
Stability Adjust R7 as described in paragraph C.
6. Turn auto voltage adjust rheostat to obtain desired
voltage.
7. The voltage regulator is now ready for load test.
8. Close output circuit breaker and apply load to
generator.
9. Verify that the voltage regulation is within + or - 1%.
If it is not within these limits, refer to troubleshooting
procedures.
10. Alternately remove and apply load to determine
whether the generator voltage is stable and response
is satisfactory.
11. If the generator voltage becomes unstable or
response is slow, adjust stability adjust R7.
a) Instability may occur when the no-load field re-
quirements of the exciter are near the minimum
working voltage of the regulator.
b) On engine driven or dc motor driven generator
sets, unstable speed governors are frequently the
cause of generator voltage instability. If a stability
problem still exists after performing the procedure as
described in paragraph C, check the governor.
12. After satisfactory initial operation has been
determined, remove load, open output circuit breaker
and stop generator set.
B. General Procedure for Subsequent Operation
of Unit
1. Verify that overvoltage circuitry and field circuit
breakers, when included in generating system, are
not tripped open.
2. In applications where generating system includes
both automatic voltage control and manual voltage
control, set the mode selector switch to AUTO
position.
3. Start generator set and bring up to rated speed.
4. Verify generator voltage. If voltage is not correct
adjust the voltage control rheostat as described in
Voltage Regulating Controls, paragraph A in this
section.
5. Close output circuit breaker or contactor and apply
load.
6. During operation periodically check system meters
to ensure that generator set is operating satisfactorily.
7. Before stopping generator set, remove load and
open output circuit breaker.

6
SECTION 4
MAINTENANCE
SAFETY SUMMARY
The precautions described in Section 2 must be
followed when inspecting, testing or making repairs to
this equipment.
PREVENTIVE MAINTENANCE INSPECTION
Semiannual inspection should be made on this unit to
insure that it is kept free of dirt and moisture. Wiring
should be inspected for satisfactory condition (ab-
sence of frayed or broken insulation) and all connec-
tions should be inspected and tightened.
TROUBLESHOOTING PROCEDURES
Troubleshooting is the process of recognizing mal-
functions of the system, intelligently analyzing the
malfunction, and making the necessary corrections to
place the unit back into proper operation. The more
common generator system malfunctions and the
appropriate repair procedures are listed in the follow-
ing Troubleshooting Chart. Following the chart are
methods of isolating system malfunctions and instruc-
tions for voltage regulator test.

7
TABLE 4-1 TROUBLE SHOOTING CHART
Voltage does not build-up to rated value
Probable Cause Probable Remedy
Voltage adjust rheostat not set correctly. Adjust rheostat.
Voltage regulator fuse (F1) blown. Install new fuse.
No field flashing voltage. Verify flashing assy. output. Refer to wiring diagrams
provided with the generator.
Circuit breaker in incoming power to voltage regulator
open.
Ascertain cause of circuit breaker trip. Correct
abnormal condition and reset circuit breaker.
Improper voltage or loose connections to regulator
power terminals L1 & L2.
Check connections. Check input voltage. Voltage
should be 120 Vac, 400 HZ, nominal.
Generator output heavily loaded or shorted. Remove short or excessive load.
Regulator rectifier assembly BR1 or BR2 open or
shorted.
Test rectifiers.
Magnetic amplifier MA-1 or MA-2 open. Check continuity of magnetic amplifier windings.
Replace amplifiers if windings are open.
Loose connections to exciter field (Terminals F+ F-) Check connections.
Defective exciter or generator. See generator manual.
Low Voltage
Open Rectifier in assembly BR1 or BR2. Test. Replace if any of its rectifiers are defective.
Preamplifier (PC board) failure. Replace PC board.
Voltage adjust not properly adjusted. Adjust rheostat.
Voltage range adjust R3 requires adjustment. Adjust for minimum voltage while external voltage
adjust is turned to complete counterclockwise position.
High Voltage
Voltage adjust rheostat not properly adjusted. Adjust rheostat.
Voltage range adjust R3 requires adjustment. Adjust for maximum voltage while voltage adjust is
turned to complete clockwise position.
Preamplifier (PC board) defective. Replace PC board.
Magnetic amplifier MA-1, MA-2 shorted. Check for shorts.

8
Sensing open or wrong sensing taps. Check wiring. If correct check for open sensing
transformer T1 or T2.
Excessive voltage applied to regulator power input
(terminals L1 & L2).
Check wiring. Voltage should be 120 Vac, 400 HZ,
nominal.
Voltage Unstable
Stability adjust potentiometer R7 not properly set.
(Stability insufficient).
Adjust R7 as described in chapter 3.
Slow Response
Excessive load. Remove excessive load.
Stability adjust R7 not properly set. Adjust R7 as described in Chapter 3.
Poor Regulation
Excessive load. Remove excessive load.
Stability adjust R7 not properly set. Adjust R7 as described in chapter 3.

9
THREE PHASE SENSING
Magnetic Amplifier
Regulator Part No.
Sensing Volts AC Paralleling
800-84132-12 120/139 No
800-84132-23 120/139 No
800-84132-25 120/139 Yes
800-84132-30 120/139 Yes
800-84132-14 208/240 Yes
800-84132-15 208/240 Yes
800-84132-16 208/240 Yes
800-84132-17 208/240 Yes
800-84132-19 208/240 Yes
800-84132-24 208/240 Yes
800-84132-28 208/240 No
800-84132-29 208/240 Yes
800-84132-31 208/240 Yes

Kato Engineering, Inc. |P.O. Box 8447 |Mankato, MN USA 56002-8447 | Tel: [phone]
[email protected] |www.KatoEngineering.com |Fax: [phone]
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